Condensation products



Patented Oct. 11, 1938 CONDENSATION PRODUCTS Walter Bauer, Darmstadt,Germany, assignor "hm & Haas Company, Philadelphia, Pa.

No Drawing. rial No. 1936 Application December 20, 1937, Se- 180,834. InGermany December 28,

9 Claims. (01. 260-2) This invention relates to condensation .productsof methacrylic amide and formaldehyde. It relates more particularly tothe polymeric form of such products, obtained by the action of form- 5aldehyde on methacrylic amide either in the polymeric or monomeric form,subject in the latter case to a simultaneous or subsequentpolymerization of the product.

This applicationis a continuation-in-part of my copending applicationSerial No. 108,115, filed October 28, 1936.

Methacrylic amide is a crystalline substance having, the formulaCH2=C(CHa)CONH2 which melts at 108 C. and is soluble in water and mostorganic solvents such as methyl and ethyl alcohols, acetone, ethylacetate, benzene, petroleum ether, etc. Itpolymerizes readily to aglassy or powdery material which may or may not be soluble in water,depending on the conditions under which it was polymerized. When themethacrylic amide is polymerized in aqueous solution, the result is ahighly viscous material which will yield films or blocks-of glass-clearpolymer on evaporation of the water. Such polymers, however,

.25 swell readily in water, and even form thick gels.

For many purposes it is desirable to render the polymeric methacrylicamide insoluble in water or at least to reduce the effect of waterthereon to a minimum.

It is an object of this invention to provide a method whereby thepolymeric methacrylic amide can be converted to a substance of greatlyincreased resistance to the action of water and other liquids which havea solvent or swelling action on the ordinary polymeric methacrylicamide.

This may be accomplished by long continued heating of the aqueoussolution of the polymer but it is preferable to treat the solublepolymer 40 with formaldehyde. This treatment may be carried out in theaqueous solution directly, or a film of the polymer may be prepared andeither immersed in an aqueous solution of formaldehyde or exposed to thevapors thereof for various lengths of time depending on the desiredresult. Polymeric methacrylic amide which is soluble in inert organicliquids may be treated in such solution with para-formaldehyde or themonomeric amide and the aldehyde can be dissolved in water or othersuitable solvent and heated in which case polymerization andcondensation of the amide with the aldehyde take place simultaneously.

When the reaction between the polymeric u methacrylic amide and theformaldehyde is carried out in an aqueous medium, it is often desirableto have a polyhydric alcohol such as glycol or glycerine present. Theseact as plasticizers for the finished product especially when it is to beused for purposes where resistance to water 5 is not paramount.

The condensation product may be still further hardened by carrying outthe condensation in the presence of water-soluble salts of a diortrivalent metal such as zinc, aluminum, iron or 10 chromium. These saltsmay be the formates, acetates, chlorides, sulfates, etc. Aluminumformate has been found to be very effective in hardening thecondensation product. The salts exert the same effect when they arepresent during the 15 combined polymerization and condensation process,or when they are used to treat the final product, as they do whenpresent during the condensation of the polymethacrylic amide and theformaldehyde. 20

The methacrylic amide, in monomeric or poly- I meric form, may be usedalone or it may be used as a joint polymer with other polymerizablecompounds such as esters of acrylic and methacrylic acids, vinyl esters,etc. 5

Example 1 A solution is made up containing four parts by weight ofpolymeric methacrylic amide, three partsof glycerine, eighteen parts ofwater, two parts of 30% aqueous formaldehyde, five parts of 5% boricacid solution and one part of aluminum formate. This solution is thenheated for one hour at 70 C. The aldehyde and amide react but noprecipitate is formed during this 35 time. The solution is then pouredout on a glass plate and dried at about 50 to C. In this manner a filmis formed which is insoluble in a water and which exhibits practicallyno swelling even on immersion in water for several days. 40 Instead ofpreparing a film as above, a thicker slab or block may be prepared inthe same way.

Example 2 2.1 parts of monomeric methacrylic amide is dissolvedin 4.0parts of toluene and 0.8 parts of 45 para-formaldehyde added. Thesolution is then heated for several hours. At first the solution isperfectly clear but as the heating is continued a solidprecipitate formswhich is insoluble in all ordinary solvents. 50

Example 3 A film prepared by evaporating a solution consisting of tenparts of polymeric methacrylic amide, ten parts of glycerine and eightyparts of 66 water is immersed at room temperature in a 10% formaldehydesolution for 2 to 6 hours. The resulting film is insoluble in water. Byusing 20% formaldehyde solution the same result can be achieved inshorter time. Increasing the temperature also shortens the timenecessary for hardening the film.

Example 4 I A film prepared as in Example 3 is hardened and renderedinsoluble in water by suspending it over a 30% formaldehyde solution atordinary or somewhat elevated temperature for a'period of 5 to 20 hours.

Example 5 Five parts of 30% formaldehyde solution is added to onehundred parts of a 10% solution of monomeric methacrylic amide and theresulting solution heated to C. for 1 hours. At the end of this time awater-insoluble gel is formed. Using ten parts of 30% formaldehyde andheating as above the insoluble gel is formed in about 45 minutes. If itis desired to prepare films or blocks from these solutions by pouring orcasting, the heating time should be reduced to about one-half and thefinal hardening carried out after evaporation of the water. By dryingsuch films or blocks two to three hours at C. a glass-clear product isobtained which is not dissolved by water.

In all cases the hardening may be accelerated by using largerproportions of formaldehyde and by carrying out the process at elevatedtemperatures.

The material thus prepared is thermoplastic and can be used for moldingpurposes, either in powder or sheet form, in the type of apparatususually employed for such molding.

Films of these polymeric condensation products can be used for coatingother films such as those made from cellulose esters, polyvinyl esters,polyacrylic and methacrylic esters, polystyrol, etc. Plasticizers mayalso be added such as polyhydric alcohol like glycol or glycerine andtheir ethers and esters. These plasticizers improve the stability of thesolutions of polymethacrylic acid amide. In some cases it may benecessary to use an adhesive layer to unite the base film with that ofthe polymethacrylic amide-formaldehyde film. Suitable adhesives arebalsams and thin film of polyacrylic acid esters. Films coated with thepolymethacrylic amide-formaldehyde condensations product may be used ina manner similar to such films coated with gelatine, as for example inphotographic work. The condensation products described herein have amuch greater resistance to water than hardened gelatine. As compared tothe latter product the new products have the decided advantage that theymay be prepared always in standard quality.

I claim:

1. In the process of preparing condensation products from methacrylicamide and formaldehyde the improvement which comprises carrying out thecondensation in the presence of a soluble salt of a metal of the groupconsisting of aluminum, zinc, iron and chromium.

2. In the process of condensing polymeric methacrylic amide withformaldehyde the improvement which comprises carrying out thecondensation in the presence of a soluble salt of a metal or the groupconsisting of aluminum, zinc, iron and chromium.

3. In the process of preparing condensation products from methacrylicamide and formaldehyde the improvement which comprises carrying out thecondensation in the presence of a soluble salt of aluminum.

4. In the process of condensing polymeric methacrylic amide withformaldehyde the improvement which comprises carrying out thecondensation in the presence of a soluble salt of aluminum.

5. In the process of preparing condensation products from methacrylicamide and formaldehyde the improvement which comprises carrying out thecondensation in the presence of aluminum formate.

6. In the process oi. condensing polymeric methacrylic amide withformaldehyde the improvement which comprises carrying out thecondensation in the presence of aluminum iormate.

7. The process which comprises condensing a joint polymer of methacrylicamide and another polymerizable organic compound with formaldehyde inthe presence of a soluble salt 01' a metal of the group consisting ofaluminum, zinc, iron and chromium.

8. The process which comprises condensing a joint polymer of methacrylicamide and another polymerizable organic compound with formaldehyde inthe presence of a soluble salt of aluminum.

9. The process which comprises condensing a joint polymer of methacrylicamide and an ester of one oi. the group consisting of acrylic andmethacrylic acids with formaldehyde in the presence of a soluble salt ofa metal of the group consisting of aluminum, zinc, iron and chromium.

WALTER BAUER.

